Abstract: In conjunction with water, a mixture can be used to prepare a sprayable slurry that hydrates to form a machinable plaster composition. The mixture includes from about 80% to about 98% by weight calcium sulfate hemihydrate, from about 1% to about 5% by weight adhesive binder for adhering said plaster mixture to a substrate and from about 0.001% to about 10% of a polysaccharide. The mixture is made into a slurry by the addition of from 10% to about 50 weight water based on the weight of the mixture.

Abstract: A mixture is used in conjunction with water is used for preparing a slurry that hydrates to form an exterior gypsum cement. The mixture includes 30-70% by weight hydraulic cement, 30-70% by weight calcined gypsum and 0.05-2.5% polycarboxylate. When the mixture is added to water less than 40 weight % based on the weight of the mixture, a slurry is formed that expands very little while it cures.

Abstract: An apparatus for mixing an additive into a fluid to form a settable mixture includes a main fluid passageway having an inlet for receiving a supply of the fluid and an outlet for dispensing the fluid, the passageway having a longitudinal axis. The apparatus includes a control valve defining a portion of the main fluid passageway and configured for selectively controlling the flow of fluid in the passageway, an additive injector disposed in the passageway and having an emitter disposed in close relationship with the axis and oriented toward the outlet. A static mixer is disposed between the injector and the outlet for enhancing the uniform mixing of the additive and the fluid. Connection points between the inlet, the valve and the static mixer are configured for smooth transition of fluid and the prevention of at least one of the collection and premature setting of the mixture.

Abstract: An apparatus for mixing an additive into a fluid to form a settable mixture includes a main fluid passageway having an inlet for receiving a supply of the fluid and an outlet for dispensing the fluid, the passageway having a longitudinal axis. The apparatus includes a control valve defining a portion of the main fluid passageway and configured for selectively controlling the flow of fluid in the passageway, an additive injector disposed in the passageway and having an emitter disposed in close relationship with the axis and oriented toward the outlet. A static mixer is disposed between the injector and the outlet for enhancing the uniform mixing of the additive and the fluid. Connection points between the inlet, the valve and the static mixer are configured for smooth transition of fluid and the prevention of at least one of the collection and premature setting of the mixture.

Abstract: A plaster mixture for forming a machinable composition, includes calcium sulfate hemihydrate; an internal lubricating dispersable binder, and an adhesive binder for adhering the plaster mixture to a substrate. In the preferred embodiment, the composition includes calcium sulfate hemihydrate, a poly(ethylene glycol) internal binder, and an ethylene/vinyl acetate copolymer adhesive binder.

Abstract: A slurry spray machine for spraying a settable slurry includes a main passageway configured for receiving a supply of pressurized slurry and having a supply end and an outlet end opposite the supply end. A first compressed gas inlet is disposed intermediate the supply and outlet ends and in fluid communication with the passageway for introducing a first supply of pressurized gas into the slurry, and a second pressurized gas inlet is disposed closer to the outlet end than the first inlet and in fluid communication with the passageway for introducing a second supply of pressurized gas into the slurry. A pressurized supply of adjuvant is provided in fluid communication with the second pressurized gas inlet for providing a blended gas to the second gas inlet. At least one valve is provided for controlling the flow of slurry through the passageway and the flow of the first and second gases into the passageway.